High-friction cermet material

ABSTRACT

A high-friction material characterized in that it incorporates boron nitride taken in an amount between 2 and 10 percent of the total weight, the rest of the ingredients being used in the following amounts: COPPER, 6 TO 15 WT.%; GRAPHITE, 3 TO 11 WT.%; BORON OXIDE, 4 TO 10 WT.%; SILICON CARBIDE, 4 TO 10 WT.%; IRON, THE BALANCE.

Elite States Eatent [1 1 Kestner et a1.

[ Dec. 10, 1974 1 HIGH-FRICTION CERMET MATERIAL [76] Inventors: Olga Evgenievna Kestner, ulitsa Baumana 43/1, kv. 12; Vasily lvanovich Vinokurov, ulitsa Spartakovskaya, 20/34, kv. 39; Irina Petrovna Axenova, ulitsa Garibaldi 8, korpus 2, kv. 63; Galina Tadeushevna Ozemblovskaya, 2 Novopodmoskovny pereulok 5, kv. 72; Amayak Pogosovich Shakhpenderian, Frunzenskaya Naberezhnaya 28, kv. 114; Anatoly Alexeevich Shagurin, lzmailovsky bulvar, 51/14, kv. 48; Larisa Nikolaevna Popova, Bratskaya ulitsa 23, korpus 1, kv. 107, all of Moscow; Ivan Ivanovich Zverev, ulitsa Sovetskaya 7/9, kv. 23, Balashikha Moskovskoi oblasti; Sergei Sergeevich Kokonin, prospekt Lenina 27, kv. 12, Balashikha Moskovskoi oblasti; Anatoly Alexandrovich Matveer, prospekt Lenina 47a, kv. 40, Balashikha Moskovskoi oblasti; Alexandr Mikhailovich Petrunin, prospekt Lenina 53, kv. l4, Balashikha Moskovskoi oblasti; Evgeny Sergeevich Sherstnev, ulitsa Sovetskaya, 16a, kv. 59, Balashikha Moskovskoi oblasti; Anatoly Alexeevich Akimtsev, prospekt Lenina 8, kv. 35, Balashikha Moskovskoi oblasti; Nikolai Mitrofanovich Sklyarov, ploschad I Vosstania l.kv. 396. Moscow. all of USSR.

22 Filed: Mar. 1, 1974 21 Appl. No.: 447,246

[52] US. Cl 29/1825, 29/1828, 75/123 R, 75/125 [51] Int. Cl. C22c 29/00 [58] Field of Search.. 75/123 R, 125, 123 B, 123 L, 75/204, 205, 206; 29/1825, 182.8, 182.7

[56] References Cited UNITED STATES PATENTS 3,151,994 10/1964 Adlassnig 29/1825 X 3,468,658 9/1969 Herald et a1. 75/123 R X Primary ExaminerL. Dewayne Rutledge Assistant ExaminerArthur J. Steiner Attorney, Agent, or Firm-Waters, Roditi, Schwartz & Nissen [5 7] ABSTRACT 1 Claim, N0 Drawings HIGH-FRICTION CERMET MATERIAL The present invention relates to powder metallurgy, and more specifically to a high-friction cermet material which may be used to advantage as rubbing surfaces of braking contrivances in the aircraft, automotive, tractor and machine tool industries and also in shipbuildmg.

There is known a high-friction cermet material based on iron and composed in the following way:

copper, wt.%;

silicon dioxide, 3 wt.%;

asbestos, 3 wt.%;

grapite, 9 wt.%;

boron oxide, 6 wt.%;

iron, 64 wt.%.

The known material, when tested under laboratory conditions on a machine with an averabe specific power of 25 kg-mlcm a specific brake work of 540 kgm/cm secand an initial slipping velocity of m/sec, displayed the following properties:

coefficient of friction, 0.23 to 0.29;

stability factor of coefficient of friction, 0.7 to 0.9;

maximum rate of linear wear of cermet;

micron/brake application, 22.

Disadvantages of the known material are low coefficient of friction and inadequate resistance to wear characterized by the maximum rate of linear wear.

There is also known another high-friction material which is a more advanced one and is composed in the following way:

iron, 64 wt.%;

copper, 10 wt.%;

graphite, 8 wt.%;

ferric sulphate, 5 wt.%;

silicon carbide, 5 wt.%;

boron carbide, 5 wt.%;

asbestos, 3 wt.%.

When tested under laboratory conditions on the above machine, this material displayed the following properties:

coefficient of friction, 0.37;

stability factor of coefficient of friction, 0.90;

linear wear, micron/brake application, 6.0.

Yet, at the end of a protracted test the coefficient of friction lowers by an amount which impairs the braking moment of the contrivance in which said material is being used. Furthermore, since in a braking contrivance the friction material mates another material, say cast iron, it is an essential requirement that the former does not abrade the latter. The friction material referred to above displays a considerable abrading effect on the material which it mates, the rate of linear wear of cast iron being 5.5 microns/brake application by way of illustration.

It is an object of the present invention to provide a high-friction cermet material of a composition which will ensure a high and invariably stable coefficient of friction, high resistance to wear and low abrading effect of the high-friction material on the material it mates.

Said and other objects are attained by the fact that in a high-friction cermet material based on iron and containing copper, graphite, boron oxide and silicon carbide there is introduced, according to the invention, boron nitride taken in an amount between 2 and 10 percent of the total weight, the rest of the ingredients being used in the following amounts:

copper, 6 to 15 wt.%;

graphite, 3 to 11 wt.%;

boron oxide, 4 to 10 wt.%;

silicon carbide, 4 to 10 wt.%;

. iron, the balance.

The essence of the invention is that in the highfriction material disclosed the silicon carbide improves the coefficient of friction and the boron nitride imparts lustrousness and smoothness to the rubbing surface, adding thereby to both the coefficient of friction and the resistance to wear of the cermet in operation. Thanks to that, the material disclosed has an invariably stable coefficient of friction and a high resistance to wear with the result that the specific power of braking contrivances can be increased and so can be the operating temperature, this latter being as high as 600C.

Tests have proved that the material disclosed, which is intended for usein braking contrivances, displays the following properties:

coefficient of friction, 0.37 to 0.40;

stability factor of coefficient of friction, 0.80 to 0.90;

maximum rate of linear wear, micron/brake application, 6 to 8.

The essence of the present invention will be best understood from the following example describing the composition of the high-friction cermet material disclosed and a method for preparing same.

The material was prepared by a technique adopted in powder metallurgy consisting in pressing the feedstock into briquets with a density between 5.2 and 5.4 g/cm followed by sintering at l,020 to 1,040C in an atmosphere of hydrogen (or dissociated ammonia) under a pressure between 20 and 30 kg/cm for 2 or 2.5 hours. The density of the sintered material was 5.5 to 5.7 g/cm and the Rockwell hardness number was between 80 and 105.

The properties of the high-friction material disclosed which were obtained under laboratory conditions using a machine with an average specific power of 25 kgm/cm a specific brake work of 540 kg-m/cm .sec and an initial slipping velocity of 20 m/sec are tabulated below against the chemical composition of said material.

Table Composition, Properties Nos. lron Cop- Boron Sili- Boron Gra- Coef- Stabi- Rate of wear per per nitcon oxide phitc ficility brakc application,

ride carent of factor micron bide fricof co- Cer- Matting tion effimet material cicnt matea ir n) of fricrial tion I 6 4 8 7 5 0.373 0.82 6.4 3.l 2 64 15 8 4 5 4 0.405 0.90 8.] 2,3 3 69 I0 3 5 4 3 0.386 0.80 7.6 2.7

It will be noted from the above specification that the high-friction cermet material disclosed is an efficient material for friction lining of rubbing surfaces in machines and mechanisms, these uses being derived from such properties as high coefficient of friction and resistance to wear, low abrading effect on the mating mate-' rial.

What is claimed is:

iron, the balance. 

1. A SINTERED HIGH-FRICTION CERMENT MATERIAL CONSISTING ESSENTIALLY OF BORON NITRIDE, 2 TO 10 WT.%; COPPER, 6 TO 15 WT.%; GRAPHITE, 3 TO 11 WT.%; BORON OXIDE, 4 TO 10 WT.%; SILICON CARBIDE, 4 TO 10 WT.%; AND IRON, THE BALANCE. 